High modulation frequencies increase loudness because spectral spread outweighs temporal fluctuation

Evidence

For 16 Hz, the specific loudness is given at four critical-band rates in the upper left part. The total loudness is plotted in the lower part and indicates a loudness almost independent of time, although the specific loudnesses at each critical-band rate vary strongly as a function of time. The total loudness remains at a value somewhat below 3 sone. For 160 Hz modulation frequency, however, specific loudnesses in each channel remain almost constant. Even though their peak values remain somewhat less than the peak values reached for low modulation frequency, the sum of all these time independent specific loudnesses (upper right parts in Fig. 8.22) leads to a total loudness near 4.5 sone, as indicated in the lower part of the figure. This loudness is larger than the peak value reached for a modulation frequency of 16 Hz and corresponds to the increment of loudness level shown in Fig. 8.2l. This result indicates that the model simulates temporal and spectral effects very well. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1303

Categorization

• XREF: Connects to the loudness model’s handling of amplitude-modulated tones and to how the brain integrates spectral space versus time — parallels the figure-ground-field distinctions in The Soundscape.